Methods for infiltrating porous carbonaceous preforms with a molten silicon or silicon alloy infiltrant to form silicon carbide bodies are disclosed, for example, in U.S. Pat. Nos. 4,889,686: 4,944,904: 4,981,822: 5,015,540: 5,021,367: and 5,043,303, incorporated herein by reference. Briefly described, the infiltration method comprises forming an assembly of the porous carbonaceous preform and means for contacting the preform with infiltrant, either by placing infiltrant directly on the preform or placing the preform and a deposit of infiltrant on a wicking material such as carbon cloth. The assembly is heated to the infiltration temperature, about 10.degree. to 20.degree. C. above the melting point of the infiltrant for a period of time to provide for infiltration of the infiltrant into the preform. A body having a silicon carbide matrix is formed in situ by the reaction bonding between the carbonaceous preform and infiltrant.
To provide for complete infiltration and filling of porosity in the preform, an excess of infiltrant is supplied to the preform. After infiltration, the excess infiltrant appears as small droplets on the surface of the reaction formed body. The infiltrant droplets can be removed from the surface of the body by diamond grinding. Besides adding an extra processing step, such grinding can reduce the strength or toughness of the body by introducing grinding defects in the surface. It is highly desirable to eliminate the excess infiltrant droplets from the surface of the reaction formed bodies to eliminate the need for post machining operations, and minimize the formation of grinding defects on the surface of the body.
One aspect of this invention is to provide a method of infiltration forming silicon carbide bodies that provides for removal of excess infiltrant from the surface of the body.
Another aspect of this invention is to provide a wicking method for removing excess infiltrant from the surface of infiltration formed silicon carbide bodies.